I am running On30 and would like to know the speed of the train by knowing the discance and the time it takes to travel the specified distance. For instance, in a test, I marked out .0742 of a mile and it took 44 seconds to travel that distance. However, I do not understand how to acurately calculate speed.
I use this calculator.
https://www.modelbuildings.org/scale-speed-calculator/
Mel
My Model Railroad
http://melvineperry.blogspot.com/
Bakersfield, California
I’m beginning to realize that aging is not for wimps.
That’s an interesting site Mel, Thanks! [Y]
Mike.
Well, if a train takes one minute to go one mile, it’s going 60 MPH. Doubling the amount of time it takes to go a mile reduces the speed by 1/2. So if it takes 2 minutes to go 1 mile, it’s going 30 MPH. 4 minutes = 15 MPH. 8 minutes = 7.5 MPH.
Once you have those as the base speeds, you can fill in the in-between. If 60 seconds = 60 MPH and 120 seconds = 30 MPH, then halfway between in time - 90 seconds - equals halfway between in speed - 45 MPH.
In US O scale, 110 real feet equals one scale mile. If you can set a speed test zone that’s 11 feet, you can calculate the speed by moving over the decimal point…if it takes a train one minute to a mile, it’s going 60 MPH; if it takes it one minute to go 1/10th of a mile, it’s going 6.0 MPH.
0.0017 mile/sec = 0.0742 mi / 44 sec
0.101 mile/min = 0.0017 mi/sec * 60 sec/min
6.07 mile/hr = 0.0017 mi/sec * 3600 sec/hr
I have a web page site which gives you two strategies to do the measuring. While I use Telegraph poles, there is no reason why the markers could not be granite veins in rock, tall pine trees, fence lines etc and I cover N HO and O in the page… Let me know if it is useful to you,
https://sites.google.com/view/stagnesrailway06
Cheers from Australia
Trevor
Speed in miles per hour is computed by dividing miles by hours.
You have to convert your measured distance into scale miles. I measured the length of my mainline with a steel tape, giving me a distance in real inches. Multiply that by 87 to make it HO inches. Divide by 12 to make it HO feet. Divide by 5280 to make it HO miles.
I used a stopwatch to time the train giving me an answer in seconds. Divide by 60 to make it minutes. Divide by 60 again to make it hours.
A calculator makes things easier.
Very good points. On my layout, it will be important to know if the train is traveling more or less than 20 mph.
“Speed” is a measure of distance in a particular time … or the time it takes to go a particular distance, like the distance between mileposts. It does not have to be expressed in a ‘standardized’ way to be useful, but by convention we’ve come to express it in distance per unit time – the time sometimes being in unit seconds, as with revolutions per second in steam locomotive design, or in unit minutes as in feet per minute, or in unit hours as in miles per hour. The unit you use depends on what you intend to do with it – and of course you can interconvert any given ‘speed’ value nto any other mathematically.
Part of the ‘unit’ choice carries over into measuring accelerations, which are in some English-unit calculations measured in ‘feet per second change per second’ (sometimes abbreviated fpsps and NOT spoken as an acronym unless you are Elmer Fudd). You could always express this in mph/s, and some people do; you can express this in a time to reach a particular distance, as in eight- and quarter-mile drag racing, or a time to reach a particular velocity, as in ‘zero-to-sixty’ times or their metric equivalent.
Europeans can screw this up in the same way they complicate mileage by expressing it in liters/100km, which aside from being a decimal number with relatively little numerical change for serious economy differences is not useful for most ‘guesstimate’ purposes regarding vehicle mileage without some conversions difficult to do in one’s head. Do not make this mistake when deciding what ‘formula’ (or algorithm) you intend to use in your particular situation.
Theoretically the ‘easiest’ way to accomplish this is to use the VASCAR method: use detectors that flag something on the locomotive or a test car very precisely – it might be when the locomotive darkens a photosensor reliably, or crosses an electrical gap, or breaks a light beam – and then precisely measures the time between two sequential activations a known distance, which can be a short distance, apart. With a reliable timebase, you can measure the time between the two activations precisely, and the result adjusted to the unit used for distance (for models that might be inches, in metric centimeters, and in SI millimeters) will give you the speed directly, which you would then convert to scale mph.
“Scale mph” of course relates to denominating the test “distance” in scale miles, or feet, or whatever, which you might mark off or ‘calibrate’ using a scale rule. That would remove some calculation steps and opportunities for ‘error’…
Europeans prefer to measure fuel consumption rather than distance per unit of fuel.
There is no reason to prefer either expression. It depends which is more relevant to you distance traveled or fuel consumed.
Just incidentally, fuel consumption is the easier of the two to use in the real world since we use both up here. Since the distance unit is conveniently decimalized your range to empty is easier to estimate.
Km/l is also not a useful measure. It would be equivalent to miles per quart, not a useful number. We buy fuel in litres, not gallons.
Measuring the scale speed of model locomotives seems absurdly obsessive given the distances are not realistic anyway.
I am just curious.
Once a train has taken 44 seconds to do a journey around the layout and there are four journies per day; when does the next train depart? Do you wait a length of time before the next departure?
Just curious.
David
sc-dist sec mph
0.0742 267 1.0
0.0742 134 2.0
0.0742 89 3.0
0.0742 67 4.0
0.0742 53 5.0
0.0742 45 6.0
0.0742 38 7.0
0.0742 33 8.0
0.0742 30 9.0
0.0742 26.7 10.0
0.0742 17.8 15.0
0.0742 13.4 20.0
0.0742 10.7 25.0
0.0742 8.9 30.0
0.0742 7.6 35.0
0.0742 6.7 40.0
0.0742 5.9 45.0
0.0742 5.3 50.0
0.0742 4.9 55.0
0.0742 4.5 60.0